Take for example the Kenberry, named after the first person who invested in Nelowet’s “crazy” idea to turn french fries from a side dish into a served-alone snack. It is an order of sweet-potato fries topped with blueberry sauce.

In town from the company’s home base in Jacksonville, Fla., for this month’s opening of the Bay State’s first French Fry Heaven at the Natick Mall, Nelowet admitted the combination sounds kind of gross.

“Trust me, just try it,” he said, handing out a sample at a preopening tasting party.

Just like the owners of Shake Shack, a New York chain that opened a restaurant this spring in Chestnut Hill, and the team behind Smashburger, a Colorado-based “better burger” chain aiming to open in November in Natick’s Sherwood Plaza, Nelowet is serving fast food that he says is of better quality and healthier than its forebears.

The three newcomers picked the suburbs west of Boston to test-drive their upscale twist on the most basic American cuisine. Their selling point: food that is locally sourced whenever possible, prepared with top-quality, additive-free ingredients.

Colm O’Molloy for the Boston Globe

French Fry Heaven franchisee, Aramis Jordan, prepared an order of sweet potato fries at the new French Fry Heaven kiosk at the Natick Mall.

All that is better than many alternatives, according to Linda Nikolakopoulos, a registered dietician at the Newton-Wellesley Center for Weight Loss Surgery at Newton-Wellesley Hospital who also has a private practice on the North Shore.

She said the hamburgers served at Smashburger and Shake Shack, made from Angus beef with no antibiotics or fillers, are better than prefrozen patties with a lot of fillers, but added a caveat.

“It’s still a 500- or 600-calorie burger, and those calories are going to add up,” she said. “It’s not something that should be eaten on a daily basis, or even on a weekly basis. Once in a while, as a treat, OK, but very, very once in awhile.”

And, she asked, in a country with an obesity epidemic, is it really a good idea to be marketing french fries as a snack?

But 24-year-old Marisa Ramos of Newton said she cannot wait to grab an order of Canadian poutine fries, topped with brown gravy and mozzarella.

Ramos was shopping at the mall before French Fry Heaven opened, and said she would definitely be back, despite having spent the past year losing 100 pounds and going from size 18 to size 6.

“I run around a lot at my job, I’m always moving,” she said. “It’ll definitely be a splurge when I’m at the mall.”

Nelowet is betting that Ramos is not alone in wanting to splurge on his fries, and even pay a little more for what he is serving.

French Fry Heaven sells nothing but french fries, made with white and sweet potatoes, that can be ordered plain or with a variety of toppings, including specialty salts such as Pink Himalayan, which the menu calls “nature’s purest,” incredibly hot ghost pepper salt, and smoky bonfire.

Its first Massachusetts outpost is in a stand-alone kiosk in the Natick Mall’s food court, right next to another new chain, Cheese Boy, a specialty grilled-cheese stand with the motto, “The best things in life are cheese.”

When asked why someone would buy an order of his plain fries for $3.99 instead of walking across the food court to spend $2.79 for a large order at McDonald’s, Nelowet pulls his smartphone out of his pocket.

“Have you ever heard of dimethylpolysiloxane?” he asked, pointing to an ingredient list for McDonald’s fries that he’s looked up. “Our ingredient list has two items, potatoes and canola oil.”

But McDonald’s does not agree that its meals are any less healthy or tasty than the new competition invading the food court.

A burger and fries by Smashburger.

“Food quality is of the utmost importance to us at McDonald’s. We are an industry leader in delivering safe, quality menu items from farm to counter,” Lisa McComb, spokeswoman for McDonald’s USA, wrote in an e-mail. “From the potatoes that become World Famous Fries to the 100 percent pure beef in our burgers, we’re committed to serving our customers great food every time they visit our restaurants.”

McDonald’s frying oil contains a small amount of dimethylpolysiloxane, according to McComb, who described it as “a common ingredient used in the food industry to help prevent the oil from foaming or splattering during preparation.”

As Smashburger prepares to open in Sherwood Plaza, across Route 9 from the mall, chief executive and chairman David Prokupek also points to the quality of his chain’s food as a selling point.

He said the burgers are made with a specially designed metal tool that smashes a loosely formed ball of 100 percent certified Angus beef into a flat patty on a 400-degree grill.

“We get a really great sear,” he said. “It’s the best $5 cooked-to-order burger out there.”

Smashburger also sells french fries along with onion rings, fried pickles, chicken sandwiches, salads, and milkshakes.

Customers order at the counter and then sit down at a table, where their food is delivered in wire baskets and accompanied by real silverware.

“We’re really excited to be opening in Natick, and in five to seven years we hope to have 20 or 30 locations in Greater Boston,” Prokupek said.

Shake Shack opened its first Bay State outlet in March at the Street Chestnut Hill. A second restaurant is planned to open in Cambridge this fall. The Danny Meyer’s Union Square Hospitality Group chain of 20 restaurants in the United States and 10 abroad started as a hot dog cart in New York City.

In 2004, the company opened its first stand-alone kiosk in the city, and lines soon formed as New Yorkers waiting for a burger with Shake Shack’s signature sauce, a variety of specialty hot dogs, frozen custard, and milkshakes. The chain also offers Shackburger dog biscuits and vanilla custard with peanut butter sauce for pooches.